Evidence that Restricting Salt Isn't Good for All

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Sodium restriction has been used to help treat heart failure for many years. But new data suggest that the strategy may not be effective in preventing either additional hospitalizations or death. Could it be that salt isn't the villain we've come to think it is?

salt-shaker-1478372-639x852The 2015 Dietary Guidelines recommend no more than 2300 mg sodium per day (about 1 1/2 teaspoons of salt) for the general population. And the American Heart Association, seconds the idea of restriction, but has an even stronger stance: 1,500 mg per day. That's equivalent to almost 4 grams of salt (sodium chloride) 1 teaspoon per day. Current estimates are that we Americans consume anywhere from 3,400 to 3,700 mg of sodium per day over twice the recommended amount. On the other hand, some guidelines for patients with symptomatic heart failure (HF) prescribe sodium levels of 2,000 - 3,000 mg/day but how effective are any such restrictions in promoting the health of such patients?

The basis for the recommendation is that too much sodium can exacerbate fluid retention in the feet, ankles, legs, and lungs, with the latter making it hard to breathe the weakened heart isn't strong enough to circulate blood enough to allow the kidneys to get rid of the excess water. And as is well known, excess sodium is strongly linked to high blood pressure. And these are a solid physiological rationales for advising such patients to restrict their salt (and thus sodium intake). However, not all the evidence supports these restrictive recommendations.

Dr. Rami Doukky of the Rush University Medical Center in Chicago and colleagues studied data of 130 HF patients who followed a sodium-restricted diet (in this study defined as less than 2500 mg sodium per day), and compared them to 130 matched patients who did not have any salt restrictions. Their report is published in the journal JACC:Heart Failure. The researchers found that about 42 percent of the salt-restricted patients died over the course of a 3-year follow-up, compared to only 26 percent of the patients with no salt restrictions. The risk of death or hospitalization for HF was also significantly higher in the patients with sodium restriction.

In their conclusion, the authors write: "In symptomatic patients with chronic HF, sodium restriction may have a detrimental impact on outcome." And they urge the conduction of randomized trials to ascertain if the link they observed between sodium restriction and deterioration of HF patients' conditions is indeed causal. Because of the small size of their study, its retrospective nature, and the fact that dietary data were self-reported, we certainly concur that additional research is needed if replicated, their results have the potential to change not only the way HF patients are treated, but even recommendations for the rest of the population.